1. Field of the Invention
The present invention generally concerns safety devices for ensuring electrical grounding of two-phase and three-phase electrical equipment to protect workers during servicing or repair of the equipment. More particularly, the present invention concerns electrical grounding equipment that is capable of being easily and quickly connected to and removed from the exposed terminals of electrical equipment and is capable of being locked when connected, to ensure against inadvertent separation of the electrical grounding equipment from any of the terminals of the electrical equipment so that any electrical potential that may be applied to the grounding equipment goes to ground and protects workers to hazards of exposure to electrical potential.
2. Description of the Prior Art
During servicing and/or repair activities for electrical equipment, particularly three-phase electrical equipment having high voltage and/or high amperage requirements, to enable workers to safely service or repair the equipment, it is required that the electrical contacts or leads of the equipment be positively grounded. Thus, in the event the leads or contacts of the equipment should become electrically energized, the electrical potential will be conducted to ground from one or all of the electrical leads or connectors, thus ensuring that the workers remain safe from electrical shock.
Currently such safety equipment comprises a large flexible braided wire for each of the phase leads, which is covered with plastic sheathing. Each of the sheathed braided wires is provided with a clamp device that is closed by a bolt member to achieve clamping to the respective phase leads of the electrical equipment. Positioning and tightening of these phase lead clamps is often a laborious and time consuming matter, especially if the lighting in the vicinity of the machinery is poor, as is often the case. The sheathed braided wires are each connected by a junction connector to a sheathed ground lead which is typically composed of the same or similar sheathed braided flexible wire. The sheathed ground lead is provided with a grounding clamp that is also tightened or loosened with respect to a ground buss by means of an adjustment bolt or the like. The grounding clamp is often difficult to connect and maintain connected during the time period that is typically required for servicing of the machinery. Also, if the clamps are not properly positioned relative to the phase leads and the grounding buss, it is possible for the clamps to become loosened. In this event, the workers may be at risk for electrical shock without being aware of it. Since the clamps are often difficult to install and remove from the phase leads of the equipment or the ground buss, some workers may decide to risk working on the equipment without first taking the time and effort to first accomplish its safe grounding.
Another undesirable feature of the use of clamps for connection to the phase leads of the electrical equipment and the ground buss is the inability to accomplish positive locking of the clamps on the object being clamped. The clamps can be tightened for secure clamping force, but another worker can easily loosen the clamps, such as when equipment servicing or repair personnel temporarily leave the site of the electrical equipment, thus potentially rendering the equipment hazardous during subsequent servicing or repair. It is desirable therefore to provide a phase grounding assembly that can not only be positively clamped to the phase leads and the ground buss, but can also be positively locked to ensure against inadvertent loosening of the assembly or parts thereof by others.
Electrical clamping assemblies have been developed, such as is disclosed in U.S. Pat. No. 4,820,901 which employs an adjustable toggle linkage to enable desired forcible clamping of a welder's ground conductor to an object serving as a ground. A quick-release adjustable electrical grounding clamp is also disclosed in U.S. Pat. No. 3,840,843. An adjustable toggle actuated welder's grounding clamp is presented in U.S. Pat. No. 5,046,958. An adjustable toggle actuated wrench or clamping device is shown by U.S. Pat. No. 5,197,359, which is provided with a lock device P-H for preventing inadvertent release of the device from its clamping position. U.S. Pat. No. 4,889,021 illustrates another toggle actuated clamping device which is provided with a lock 11 to prevent its inadvertent release from its clamping position.